Different plant species, ecotypes, varieties or cultivars can be selected, tailored and harnessed for the remediation of polluted soils, sites and brownfields, as well as for the phytotreatment of domestic or industrial wastewater. Several approaches are possible, but phytoremediation does always rely on in situ extraction, detoxification or immobilization of xenobiotic chemicals or trace elements. Phytoremediation has a strong potential as a natural, solar-energy driven approach for soils and sites moderately polluted over large surfaces, if the most appropriate plants have been carefully selected and the adequate agronomic methods are applied to manage the phytoavailability of contaminants. It can already offer a sustainable and less expensive alternative to soils or sites restoration, as compared to traditional physico-chemical techniques, even if the time required reaching the target end-points is often a severe drawback. Depending on the type of soil to be treated, as well as on the pollutants, their concentration and ageing, different approaches can be considered and will be presented with some examples of successful applications, but also highlighting their limitations: • Phytoextraction - uptake of trace elements into roots, then translocation into shoots, followed by the harvest and destruction of the contaminated plants, with possible recycling strategies to recover metals from biomass or ash. Two types of plants can be used: plants able to hyperaccumulate one or several trace elements, but producing low biomass; or plants accumulating moderate amounts of metals or metalloids, but producing high biomass. • Phytostabilisation - based on the immobilization of inorganic contaminants by adsorption to plant roots or soil particles, or precipitation in the root area, thus preventing their migration in soil, groundwater or air, and decreasing erosion, runoff and leaching. For large contaminated areas phytostabilisation is probably the only reasonable option to restore ecosystems. The most effective approach is the use of indigenous plant species, after the addition of appropriate soil amendments. • Phytodegradation - exploiting the huge potential and biodiversity of plant metabolism to detoxify, transform or degrade xenobiotic organic chemicals, like pesticides, explosives or dyes. • Phytostimulation - enhanced microbial metabolism by root exudates; plant/microbial interactions are important for such rhizospheric processes, especially for very hydrophobic compounds. In spite of a growing track record of commercial success, more large-scale trials are needed to definitively prove that phytoremediation is effective and applicable in many different situations, to rigorously assess its economics and to convince stakeholders and local authorities that it is a reality, not a dream. However, to be recognized as a mature and efficient technology, phytoremediation still needs significant progress, even if it is the focus of intensive research and devel
